Easily Defeat True Orochi Boss:
When you battle Orochi, make sure both team members are attacking. Now, while controlling Asuka, have her move far away from Orochi. As Homura continues her assault, Orochi will only have time to occasionally toss projectiles your way. Just avoid them. If you avoid them for long enough, Homura (who deals more damage than Asuka) will finish the job on your behalf for an easy win.